1. Field of the Invention
The present invention relates generally to semiconductor processing equipment and more particularly to earthquake protection for such equipment.
2. Description of the Related Art
Semiconductor workpieces, or wafers, are typically loaded into wafer racks or boats for processing in a batch reactor. If the reactor is a vertical reactor, the wafer rack is typically supported on a pedestal. In the system disclosed in PCT Publication No. WO 99/38199, published Jul. 29, 1999, the pedestal, in turn, is supported on a doorplate. The wafer rack and pedestal are lifted into the reactor from below. The doorplate serves to seal the internal chamber of the reactor from a surrounding processing chamber during processing of the wafers.
The wafer carrier and pedestal are typically made of quartz, and are relatively fragile. As such, they are susceptible to damage caused by earthquakes. During an earthquake, the wafer rack has a tendency to vibrate or rock back and forth on the pedestal. Similarly, the pedestal has a tendency to vibrate or rock back and forth on the doorplate. If the vibration or rocking caused by the earthquake is significant, the wafer rack can fall off of the pedestal, and the pedestal can fall off of the doorplate. As a result, damage to the wafer rack, pedestal, wafers, and the reactor or surrounding processing chamber can occur. The loss of an entire rack of large wafers (e.g., 100) can be quite expensive.
Accordingly, a need exists for semiconductor processing equipment that is equipped to prevent damage that can be caused by earthquakes.
In accordance with one aspect of the present invention, a wafer carrier is provided comprising a wafer rack adapted to receive a plurality of wafers and a pedestal supporting the wafer rack. A lock is provided that is engageable with at least one of the wafer rack and the pedestal to selectively lock the wafer rack to the pedestal. The wafer rack is thus prevented from falling off of the pedestal as a result of earthquake-induced vibrations and accelerations.
In accordance with another aspect of the present invention, a wafer processing apparatus is provided, comprising a doorplate, a pedestal including one or more legs to support the pedestal on the doorplate, and a wafer rack positionable on the pedestal. A pedestal lock is connected to the doorplate and is selectively engageable with at least one of the legs to lock the pedestal to the doorplate. The pedestal is thereby prevented from falling off of the doorplate as a result of earthquake-induced vibrations and accelerations.